Love at first sight
by Pinklover98
Summary: What if Danny had a sister who joined the crime lab? What if Don and Danny's sister start dating? Eventual Don Flack/OC Danny/Lindsay AU story
1. Chapter 1

**Love at first sight**

 **Chapter 1**

 **Authors note: This is my first CSI:NY fanfiction, and I've been working on it a for a while to get it to the point where I'm happy with it and am ready to post it. I hope you guys enjoy this AU story and please review to let me know your thoughts.**

 **Disclaimer: I don't own any of the characters (except Lottie), or the show.**

"Flack, hey come in." Danny says, motioning for Don to enter his apartment.

"Hey, thanks." Don says heading through to the living room. He stops short in the doorway, finding a brunette, about his age, curled up in the armchair reading.

"Flack, this is Lottie. Lottie, this is Flack." Danny says, introducing them. "Make yourself at home." He says to Don. "I'll just find out where Lindsay is with Luce."

 _'He's pretty cute.'_ Lottie thinks to herself as Don walks into the room.

"Danny's told me about you." Lottie pipes up from the corner. "Sorry, hi, it's nice to meet you. Danny always says I rush into things."

"Oh uh, no that's ok." Don replies. taking a seat opposite her on the sofa.

"He's probably never mentioned me, has he?" She asks and Don shakes his head.

"No..not that I recall anyway."

"Didn't think so. He's embarrassed of me."

"Me? Embarrassed of you? Nah...not in a million years. Protective of my baby sister? Yes." Danny says as he renters the room.

' _So she's not my age_.' Don thinks to himself.

"By one minute! You're older than me by one minute Danny!" Lottie protests, shaking her head.

"You're twins?" Don asks and Lottie nods.

"Danny didn't tell you?"

"Danny doesn't talk much about his life. He didn't tell me he had a sister, let alone a twin sister." He replies and Danny shrugs.

"Not much to tell." He says. "Just don't go hitting on my sister Flack." He warns, pointing at his friend.

"Daniel!" Lottie exclaims, shaking her head.

"What?" Danny replies. "I'm just warning him." Don lets out a laugh as Lottie throws a cushion at Danny, hitting him square in the face.

"Nice shot." Don compliments her.

"Yeah, yeah, whatever. Gang up on me why don't you?" Danny complains, as Lottie and Don continue to laugh. "I'm leaving before I get abused anymore."

"Baby!" Erin calls after him. "So, what's your actual name, I'm guessing Flack's the surname?"

"Yeah, Donald Flack Jr. Don's fine though."

"Ah, a namesake huh?" Lottie says, nodding. "Me too."

"Really?" Lottie nods again.

"Lottie's short for Loretta Marie, Loretta being my Grandma Messer's name, but I can't say I particularly love the name so I go by Lottie. Danny, Papa and Louis are the only ones to call me by my full name, Danny only when he's mad, Papa and Louis all the time, they add the 'Marie' when they're mad though."

"Got it, my Ma calls me Donnie and Pops calls me Donald. Says if he and Ma wanted be to be called Don, that's what would be on my birth certificate." Lottie gives a light laugh.

"Fair enough. I'm sure my Ma would be like that."

"She uh, she passed away?" Don asks gently and Lottie nods.

"Don't really remember her too much, Danny and I were still quite young when she passed."

"What're you two talking about?" Danny asks as he enters the living room again, this time with Lucy in his arms and Lindsay behind him.

"Hey Lucy-Lu!" Lottie coos, reaching out her hands for the baby. Danny gently passes the sleepy baby over to his sister and perches on the sofa next to Flack.

"Families." Lottie says absently as she allows Lucy to play with her fingers.

"Huh?" Danny asks, switching a football game on.

Lottie rolls her eyes at Don and Lindsay before replying. "What Don and I were talking about."

"Don huh?" Danny asks, glancing between his sister and best friend. "On a first name basis now huh? Better not go any further than that."

"Danny." Lindsay scolds gently.

* * *

"So where do you work?" Flack asks as he and Lottie clean up after dinner.

"At the moment tech crimes, but I'm transfering over to the crime lab next week." Lottie replies with a smile. "You're a homicide detective right?"

"Yep. Guess we'll be seeing a lot more of each other then. I'm usually up there quite a lot." He says, drying the dish in his hand.

"Guess so." Lottie says with a smile. ' _Can't say I'll be complaining too much_.' She thinks to herself.

* * *

"I think he'd be good for her." Lindsay says to Danny later that night, as they lie in bed.

"No Montana." Danny mutters, keeping his eyes shut.

"Come on Danny." Lindsay tries again, with a small laugh.

"My sister and Flack are not gonna start dating, got it?" Danny spits out, Lindsay sighs but nods.

"Whatever you say."

 **AN: So, what do you guys think? Don't forget to leave a review!**


	2. Chapter 2

**Authors note: Sorry for the delay in posting and sorry if Danny seems a little OOC in this chapter, I've portrayed him in this way to fit with my story.**

"Hey," Don says as he enters a coffee shop near the precinct just as Lottie walks out.

"Oh, hey!" Lottie replies with a smile. "Sorry, I didn't see you there. I was in my own little world."

"Don't worry about it." Flack says with a laugh. "How's things going at the lab?"

"Good, caught my first big case in the city today, just out on a coffee run for the rest of the team. You know how bad the coffee is there."

"Oh yeah," He says with a laugh. "if you wanna wait, I'll walk back with you. I'm heading up there anyway. I'm guessing it's your case I've just been assigned to?" He asks. Lottie nods and follows him back inside.

"Guess so." She says with a shrug. "Central park murder, young girl?" Flack nods, queuing up for coffee. "If I'd known you were gonna be in the lab, I could have got you a coffee too."

"Eh, don't worry about it." Don says again as he steps up to the counter.

* * *

"What're you and Flack doing together?" Danny asks, taking the last cup coffee off Lottie as she walks down the hallway to the conference room.

"We bumped into each other at the coffee shop and walked back up here together, that's all." She replies, giving Danny a confused look. "Geez, chill bro, no need to get so jealous." She teases as she speeds up to fall in step with Stella, leaving Danny behind her, still frowning.

"Relax Danny," Lindsay says, appearing beside him. "It's not like they're dating."

"And they're not going to." Danny growls as they reach the conference room.

"So, how you finding it here so far?" Danny asks, walking into the lab where Lottie was sat, waiting for results back on some fibres she'd found at the crime scene.

"Good thanks, everyone seems really nice." Lottie replies. "I like it better here than at tech crimes, that place is boring compared to this."

"You know you can come to me, right, if you ever need anything?" Danny clarifies

"I know Danny, thanks." She says

"I mean..."

"Danny...I know." Lottie says, pressing a kiss to his cheek "Honestly Daniel, you worry about me too much. I'm fine, I can fend for myself."

"I know that Lott', doesn't mean I can't or don't worry, I am your big brother after all."

"Firstly, there's no need to, I am a big girl Danny, I'm not a baby anymore." Lottie says, punching Danny gently in the arm. "And secondly, you are not older than me. We're twins, remember? God, you're really not as smart as everyone thinks." She says teasingly.

"That one minute really counts though." Danny replies in the same tone. "Seriously though Lottie, you and Flack, what's going on?"

"Oh for goodness sake Daniel, seriously, we're talking about this again?"

"I just wanna know. You guys looked pretty...cosy...earlier..."

"Danny! We had just stepped off an extremely crowded lift, of course we were going to look...'cosy', as you put it."

"Hey, you wanna come down and interrogate this guy with me?" Don asks Lottie, poking his head around the side of the door of the lab. Lottie shoots a glance at Danny who scowls but shrugs.

"Sure, I'll meet you down there ok?" Lottie says, turning to Don with a smile.

"Sure." He replies, turning and heading for the lifts.

"Go on then, Flack's gonna be waiting for you." Danny says with a huff, shooing Lottie out the door.

"Alright, alright, I'm going! No need to get your knickers in a twist!" She teases.

"Hey Lott, you wanna go out for dinner later?" He calls after Lottie, who turns and frowns at him.

"Yeah, ok, but why?" She asks.

"Pops rang earlier, said he wanted to get all of us together or something." Danny says with a shrug. Lottie frowns but nods as she walks backwards towards the lift.

"Text me the details, ok?" She calls back over her shoulder, jumping on the lift quickly before the doors shut.

* * *

"You wanna head out for a drink? Celebrate the first case you've closed here?" Flack asks Lottie as they watch two officers escort the killer out of the room.

"I'd love to Don, but I promised Danny I'd catch up with him, I haven't been able to spend that much time with him recently." Lottie says with a small smile. "Plus, I think it was our dad who organised this whole thing, so he's not going to be happy if I don't turn up. Raincheck?"

"Yeah, sure. I'll see you around."

"See ya." Lottie calls as she heads back up to the crime lab to collect her things.

 **AN: Please review!**


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